Electric power conversion apparatus having single-phase and multi-phase operation modes

ABSTRACT

An AC/DC conversion apparatus includes first, second, and third AC/DC conversion modules operated by a controller in two modes of operation. In the first mode, the input AC signal is 3-phase and each of the three modules are enabled to handle a respective one of the input phases. In the second mode, the input AC signal is single phase and the first and second modules are enabled to deliver output power based on the single-phase AC input, while the controller actuates an H-bridge switches in the third module to which active filter circuitry is connected, to reduce an AC component in the output signal. The active filter circuitry can be selectively connected to the H-bridge switches when single-phase operation is desired, which circuitry may be disposed in a filter housing having male electrical terminals that cooperate with corresponding female terminals associated with the third module.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

BACKGROUND

a. Technical Field

The instant disclosure relates generally to power electronics systems,and more particularly to an isolated AC/DC electric power conversionapparatus compatible with multi-phase (e.g., three-phase) andsingle-phase AC input power with improved power density.

b. Background

This background description is set forth below for the purpose ofproviding context only. Therefore, any aspects of this backgrounddescription, to the extent that it does not otherwise qualify as priorart, is neither expressly nor impliedly admitted as prior art againstthe instant disclosure.

Isolated alternating current (AC)/direct current (DC) electric powerconverters can be used in many different applications. For example only,such an electric power converter can be used as a battery charger tocharge a DC battery associated with an electric-motor powered automotivevehicle. Known isolated AC/DC electric power converters may adopt threemain stages. For example, a typical configuration may be a half-bridgeresonance based isolated AC/DC converter that includes (i) a first,converter stage configured to convert grid or mains AC voltage (e.g., 50or 60 Hz) to an output DC voltage (to implement power factor correction)stored across a relative large capacitor, (ii) a second DC/AC converterstage configured to transform the rectified DC voltage to a relativelyhigh-frequency AC voltage (e.g., hundreds of kHz) applied to anelectrical isolation device—such as a transformer, and (iii) third AC/DCconverter stage configured to rectify the high-frequency AC voltagesignal to produce a final DC output voltage signal. A target battery maybe arranged to receive the final DC output voltage signal. The 3-stageconverter described above incorporates a relatively large, bulky DCcapacitor, which can, among other things, reduce power density.

With the progress of electric vehicles, the demand for electric vehiclebattery chargers is increasing. Due to different electric power gridstandards in different countries, it would be desirable for such batterychargers to accommodate both three-phase AC input power (e.g., 400 VACin Germany) as well as single-phase AC input power (e.g., 208 VAC in theUnited States). Such flexibility would shorten the product developmentperiod. Known dual-input power chargers (e.g., 3-phase, single-phase),however, exhibit relatively poor power density when operated withsingle-phase AC input power. For example, such a charger is purported todeliver ˜20 kW with three-phase AC input power, but drops to only ˜3.3kW (or 6.6 KW based on the AC input) with single-phase AC input power.

It would be desirable to provide an AC/DC electric power conversionapparatus, such as battery charger, that is capable of being configuredfor use with either multi-phase (e.g., 3-phase) or single-phase AC inputpower and that exhibits improved power density when operated withsingle-phase AC input power.

The foregoing discussion is intended only to illustrate the presentfield and should not be taken as a disavowal of claim scope.

SUMMARY

In an embodiment, an apparatus is provided for converting a first ACsignal to a DC signal. The apparatus includes an electronic controllerincluding a processor and a memory and at least first, second, and thirdAC/DC conversion modules. Each AC/DC conversion module is connected toand is controlled by the controller. The respective output signals fromthe conversion modules are electrically joined at an output node. Eachconversion module includes (i) an indirect matrix converter having aninput interface configured to receive the first AC signal and an outputinterface configured to produce a second AC signal; (ii) a transformerhaving a primary winding and an electrically isolated and magneticallycoupled secondary winding; (iii) a coupling inductor in series betweenthe output interface of the indirect matrix converter and the primarywinding; and (iv) an H-bridge switching arrangement connected to thesecondary winding and configured to produce on the output node arespective output signal having a DC component and at least one ACcomponent.

In a first mode of operation where the first AC signal comprises amulti-phase AC signal (e.g., 3-phase AC input power), the controller isconfigured to enable operation of the first, second, and third AC/DCconversion modules. In the first mode of operation, the AC component ofthe respective output signals from each AC/DC conversion module willtend to cancel each other out. In the first mode of operation, thefirst, second, and third AC/DC conversion modules all operate to deliverpower to the output node.

In a second mode of operation where the first AC signal is asingle-phase AC signal, the controller enables operation of the firstand second AC/DC conversion modules and disables operation of theindirect matrix converter portion of the third AC/DC conversion module.The controller, however, actuates the H-bridge switching arrangementcontained in the third AC/DC conversion module according to a filteringstrategy to operate active filter circuitry connected to the H-bridge,in order to reduce the AC component of the respective output signals ofthe first and second AC/DC conversion modules. In the second mode ofoperation, the first and second AC/DC conversion modules operate todeliver active power while the third AC/DC conversion module handlesactive filtering to reduce AC components of the output node.

Through the foregoing, improved power density for single-phase operationcan be realized. This is because the first and second AC/DC conversionmodules both operate while the third module is repurposed for activefiltering.

In an embodiment, the controller and the first, second, and third AC/DCconversion modules are disposed in a main housing and the active filtercircuitry comprises a tank circuit disposed in a filter housing. Thefilter housing has a first electrical coupling feature associatedtherewith and the main housing has a second electrical coupling featureassociated therewith that is complementary with the first electricalcoupling feature. These coupling features cooperate to electricallycouple the active filter tank circuit to the third AC/DC conversionmodule. For example only, the first and second electrical couplingfeatures may comprise male and female electrical terminals. Without theactive filter inserted, the apparatus can operate based on multi-phase(e.g., 3-phase) AC input power. However, when single phase operation isdesired, the filter housing can be readily plugged into the main housingto reconfigure the apparatus for use with single-phase AC input power.

The foregoing and other aspects, features, details, utilities, andadvantages of the present disclosure will be apparent from reading thefollowing description and claims, and from reviewing the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic and block diagram of an isolated AC/DC electricpower converter in accordance with an embodiment.

FIG. 2 is diagrammatic schematic and block diagram of an isolated AC/DCelectric power converter according to another embodiment.

FIG. 3 shows simplified, timing diagrams of a first set of switchcontrol signals associated with a full bridge based AC/DC rectifier ofFIG. 2.

FIG. 4 shows simplified, timing diagrams of a second set of switchcontrol signals to control the operation of the grid-side DC/ACconverter and the battery-side AC/DC rectifier (H-bridge) of FIG. 2.

FIG. 5 is a timing diagram of parameters for determining switch timingin FIG. 4.

FIG. 6 is a simplified schematic and block diagram of a modular AC/DCelectric power conversion apparatus showing first, second, and thirdAC/DC conversion modules for operating with 3-phase AC input power, inan embodiment.

FIG. 7 is a simplified schematic and block diagram of a modular AC/DCelectric power conversion apparatus showing first, second, and thirdAC/DC conversion modules and active filter circuitry, for operating withsingle-phase AC input power, in an embodiment.

FIG. 8 is a simplified schematic and block diagram of the third AC/DCconversion module of FIG. 7, showing active filter circuitry in greaterdetail.

FIGS. 9-10 are simplified, timing diagrams showing phase currents andvoltage on an output node during operation of the embodiment of FIG. 7.

DETAILED DESCRIPTION

Various embodiments are described herein to various apparatuses,systems, and/or methods. Numerous specific details are set forth toprovide a thorough understanding of the overall structure, function,manufacture, and use of the embodiments as described in thespecification and illustrated in the accompanying drawings. It will beunderstood by those skilled in the art, however, that the embodimentsmay be practiced without such specific details. In other instances,well-known operations, components, and elements have not been describedin detail so as not to obscure the embodiments described in thespecification. Those of ordinary skill in the art will understand thatthe embodiments described and illustrated herein are non-limitingexamples, and thus it can be appreciated that the specific structuraland functional details disclosed herein may be representative and do notnecessarily limit the scope of the embodiments, the scope of which isdefined solely by the appended claims.

Reference throughout the specification to “various embodiments,” “someembodiments,” “one embodiment,” or “an embodiment,” or the like, meansthat a particular feature, structure, or characteristic described inconnection with the embodiment is included in at least one embodiment.Thus, appearances of the phrases “in various embodiments,” “in someembodiments,” “in one embodiment,” or “in an embodiment,” or the like,in places throughout the specification are not necessarily all referringto the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments. Thus, the particular features, structures, orcharacteristics illustrated or described in connection with oneembodiment may be combined, in whole or in part, with the features,structures, or characteristics of one or more other embodiments withoutlimitation given that such combination is not illogical ornon-functional.

Referring now to the drawings wherein like reference numerals are usedto identify identical or similar components in the various views, FIG. 1is simplified schematic and block diagram of an isolated AC/DC electricpower conversion apparatus 20 (hereinafter “conversion apparatus”). Theconversion apparatus 20 of FIGS. 1-2 may form a module that can bereplicated and deployed in parallel to form a multi-module conversionapparatus—described in detail in FIGS. 6-10. The modular conversionapparatus is configured to operate with both 3-phase AC input power aswell as with single-phase AC input power. It exhibits improved powerdensity when operated with single-phase AC input power as compared toconventional approaches.

As noted in the Background, conventional approaches exhibit poor powerdensity when operated with single-phase AC input power. In this regard,while conventional 3-phase AC/DC conversion devices (e.g., chargers)could work with single phase input, they typically lack filtering forsingle phase operation, and thus the current ripple on the output wouldlimit operating (output) power to a low level, resulting in poor powerdensity with single phase power input. Implementing active filtering asa solution to the above would require additional switches andmicro-controller, which would increase the cost and development period,as well as also reducing power density. The present teachings addressand overcome these shortcomings.

In the illustrated embodiment, the conversion apparatus 20 is coupled toan AC input power source 22 and has an input inductor 24 configured tosmooth the grid-side current. The conversion apparatus 20 is furtherconfigured to output a DC voltage signal on an output node 26, which canbe used to charge a re-chargeable battery 27, such as an electricvehicle (EV) battery, for example only. The battery 27 is shown toinclude a battery voltage source portion 28 (sometimes referred toherein as V_(b) or V_(BAT)) and a battery resistance 30 (sometimesreferred to herein as R_(b)). The AC source 22 (AC power source) isconfigured to provide an AC input current at a specified AC inputvoltage level. The AC source 22 may be a main AC power supply orelectrical system for a building or the like provided within an overalllarger AC electric power grid (hereinafter sometimes referred to as gridpower, grid voltage, grid-side, etc.). The AC source 22 may besingle-phase or multi-phase (e.g., 3-phase). Depending on location, theAC source 22 may output 120 volts or 240 volts at 60 Hz, 110 volts or220 volts at 50 Hz, or 380-480 volts at 50 Hz (3-phase power). Thevoltage V_(b) of re-chargeable battery 27 may be nominally between about200-500 VDC. In an embodiment, the conversion apparatus 20 may have anoutput voltage of about 360 V.

The conversion apparatus 20 includes two main stages, wherein a firststage 32 comprises an AC/AC converter 34 and a second stage 36 comprisesan AC/DC rectifier 38. The stages are electrically isolated but coupledby way of a transformer 40 having a primary winding 42 and a secondarywinding 44.

The first stage 32 may comprise an indirect matrix converter (MC) as theAC/AC converter 34, and may comprise conventional approaches forconstructing the same as known in the art. It should be understood,however, that converter 34 may comprise a true matrix converter. Theindirect matrix converter type AC/AC converter 34 has minimal energystorage requirements, which eliminates the need for bulky andlifetime-limited energy-storing capacitors, and exhibits improvedefficiency, for example, by merging three-stages as known in the art(see Background) down to two-stages, and as seen by reference to U.S.patent application Ser. No. 14/789,412, filed 1 Jul. 2016, (hereinafterthe '412 application, entitled “ELECTRIC POWER CONVERSION APPARATUS”),which '412 application is hereby incorporated by reference as thoughfully set forth herein. Eliminating the DC-bus capacitor can alsoincrease the power density of the overall apparatus.

FIG. 2 shows an electric power conversion apparatus, designated 20 a,that features an indirect matrix converter. Conversion apparatus 20 aincludes two main stages, namely, a first stage 32 that includes anAC/AC converter in the form of an indirect matrix converter and a secondstage 36 that includes an AC/DC rectifier part 36.

On the input (grid) side, FIG. 2 shows AC (grid) source 22, which may bea single-phase, 60 Hz, 120 volt alternating current (AC) voltage signalor alternately a single-phase 50 Hz AC signal, or a multi-phase (e.g.,3-phase) alternating current (AC) source. On the output (battery) side,FIG. 2 shows a rechargeable battery V_(b) with battery resistance R_(b).

The first stage 32 includes an input inductor 24 (sometime referred toas “L”), an indirect matrix converter, a coupling inductor L_(s), andtransformer 40, which includes primary windings 42 and secondarywindings 44.

The input inductor 24 is electrically coupled in series with AC source22 and is configured to smooth the grid-side current in respect of ACsource 22. The size of inductor 24 will depend on the degree ofsmoothing and the switching frequency. In an embodiment, inductor 24 maybe about 10 micro-henry (μH).

In an embodiment, the indirect matrix converter includes a full bridgerectifier 66 (AC/DC converter), a filter capacitor designated C_(in),and a DC/AC full bridge converter 68. The indirect matrix converter isconfigured for AC/AC conversion and further includes an input interfaceconfigured to receive a first AC signal from AC source 22 and an outputinterface configured to produce a second AC signal. As shown in FIG. 2,the input interface of the indirect matrix converter is coupled to bothsides of the AC source 22 through inductor 24. The output interface ofthe indirect matrix converter is coupled to both ends of the primarywinding 42 through the coupling inductor L_(s).

Full bridge rectifier 66 constitutes a means for rectifying the firstalternating current (AC) input signal at node 74 (i.e., which presentsat a first, grid frequency, for example, 60 Hz) and producing a firstrectified output signal at node 76. The first rectified signal includesa first direct current (DC) component. Rectifier 66 may include foursemiconductor switches, designated M₁, M₂, M₃, M₄, arranged in a fullbridge configuration and operating at the grid frequency. The switchesM₁, M₂, M₃, M₄ may comprise conventional semiconductor switches known inthe art, such as MOSFET or IGBT devices. In an embodiment, the switchesM₁, M₂, M₃, M₄ may comprise an N-Channel power MOSFET provided under thetrade designation and/or part number STY139N65M5 fromSTMicroelectronics, Coppell, Tex., USA.

Capacitor C_(in) is connected across the output of rectifier 66, betweennode 76 and a ground node 78. Capacitor C_(in) is configured in size tofilter high-frequency harmonics from the rectified signal at node 76(e.g., relatively small: ˜uF level). It should be understood that C_(in)is not used for energy storage, but is rather used for filteringpurposes, and is thus not a large, bulky DC-bus capacitor as is typicalfor conventional 3-stage converters where the DC-bus capacitor may be onthe order of millifarads (˜mF). This reduced size in C_(in) can increasethe power density and extend the service life of the conversionapparatus 20 a.

The DC/AC converter 68 is electrically connected to the output ofrectifier 66 (i.e., connected across nodes 76, 78). The DC/AC converter68 is configured to convert the first DC (rectified) signal on node 76into a second AC signal. As illustrated, DC/AC converter 68 may comprisefour semiconductor switches, designated S₁, S₂, S₃, S₄, and arranged ina full bridge configuration operating at a second frequency, namely, aswitching frequency f_(s). The second, switching frequency f_(s) isgenerally much higher than the first, grid frequency. In an embodiment,the second, switching frequency may be in a range of between about 135kHz to 500 kHz, while the first, grid frequency may be 60 Hz (or 50 Hz).The semiconductor switches S₁, S₂, S₃, S₄ may comprise commerciallyavailable components known in the art.

Inductor L_(s) is electrically connected in series between the DC/ACconverter 68 and primary winding 42.

Transformer 40 constitutes an electrical isolation device and includes aprimary winding 42 and an electrically isolated and magnetically coupledsecondary winding 44. As known, transformer 40 is characterized by aturn ratio between the secondary winding and the primary winding.

The second stage 36 of conversion apparatus 20 a includes an AC/DCconverter 70 and an output capacitor designated C_(o).

AC/DC converter 70 is electrically connected to the second winding 44 oftransformer 40 and is configured to convert or rectify the AC signalinduced on the secondary winding 44 to a second rectified output signalon output node 80. The output signal produced on the output node 80 fromthe single phase conversion device 20 a has a DC component and at leastone AC component, wherein the at least one AC component includes asecond order harmonic of the grid frequency (e.g., a 120 Hz componentsfor a 60 Hz grid frequency).

In the illustrated embodiment, the AC/DC converter 70 may comprise foursemiconductor switches, designated switches S₅, S₆, S₇, S₈, arranged inan active H-bridge (full) switching arrangement 70. In an embodiment,H-bridge switching arrangement 70 is controlled to operate at theabove-mentioned switching frequency f_(s) (i.e., switches S₁˜S₈ arecontrolled to operate at the same switching frequency f_(s)). Thesemiconductor switches S₅, S₆, S₇, S₈, may comprise commerciallyavailable components, for example, a GaN High Electron MobilityTransistor (HEMT) device, such as an enhancement mode GaN transistorprovided under the trade designation and/or part number GS66516T fromGaN Systems Corp., Ann Arbor, Mich., USA.

Output capacitor C_(o) is connected across the output of H-bridge 70between output node 80 and an output ground node 82 and is configured insize to filter high-frequency harmonics from the output signal at node80 (e.g., relatively small: ˜uF level). In an embodiment, capacitorC_(o) may be about 100 μF.

Conversion apparatus 20 a further includes an electronic control unit 46(hereinafter controller 46) configured to implement a desired controlstrategy for the operation of conversion apparatus 20 a. Controller 46includes a processor 48 and a memory 50. Processor 48 may includeprocessing capabilities as well as an input/output (I/O) interfacethrough which processor 48 may receive a plurality of input signals andgenerate a plurality of output signals (e.g., gate drive signals forswitches M₁˜M₄ and S₁˜S₈). Memory 50 is provided for storage of data andinstructions or code (i.e., software) for processor 48. Memory 50 mayinclude various forms of non-volatile (i.e., non-transitory) memoryincluding flash memory or read only memory (ROM) including various formsof programmable read only memory (e.g., PROM, EPROM, EEPROM) and/orvolatile memory including random access memory (RAM) including staticrandom access memory (SRAM), dynamic random access memory (DRAM) andsynchronous dynamic random access memory (SDRAM). Although not shown inFIG. 2, conversion apparatus 20 a may also include a driver circuit tointerface between the outputs of controller 46 and the gate terminals ofthe semiconductor switches. In an embodiment, such gate drive devicesmay comprise commercially available components, such as a commerciallyavailable chip known in the art, for example, a gate drive chipavailable under part number IXD_614 from IXYS Corporation, Milpitas,Calif., USA.

Memory 50 stores executable code in the form of main control logic 51,which is configured to control the operation of conversion apparatus 20a in accordance with a desired control strategy. Main control logic 51,when executed by processor 48, is configured to generate, in response toone or more input signals, the various gate drive signals for theswitches M₁˜M₄ and S₁˜S₈. Main control logic 51 may include programmedlogic blocks to implement specific functions, including withoutlimitation rectifier logic 58, power factor correction (PFC) logic 60,zero voltage switching (ZVS) logic 62, and active filter duty cyclecontrol logic 64. The active filter duty cycle control logic 64 will bedescribed in greater detail below in a multi-phase, modular electricpower conversion apparatus embodiment.

The grid rectifier logic 58 is configured to generate the gate drivesignals for switches M₁˜M₄ of rectifier 66. To accomplish this,conversion apparatus 20 a may include a grid voltage sensor 52 (shown inblock form) configured to output a signal indicative of a grid voltage,including a polarity (i.e., positive or negative). The voltage sensor 52may be disposed on the grid side (i.e., electrically connected to ACsource 22) to monitor the grid voltage. In an embodiment, grid voltagesensor 52 may comprise conventional components known in the art.

FIG. 3 shows timing diagrams of the gate drive signals (i.e., switchcontrol signals) produced by the grid rectifier logic 58 of controller46. The M₁˜M₄ based H-bridge rectifier 66 will rectify the grid ACvoltage into a DC voltage. The switching frequency of M₁˜M₄ is the sameas the grid voltage (e.g., 50-60 Hz). Note, that M₁˜M₄ are controlled bythe detecting the polarity of the grid voltage. Thus, when the gridvoltage is positive, M₁ and M₄ are turned on (i.e., the V_(GS) of M₁ andM₄ is high). When the grid voltage is negative, M₂ and M₃ are turned on.The gate drive signals for switches M₁ and M₄ operate in unison whileswitches M₂ and M₃ operate in unison. Additionally, the combination ofM₁M₄ are complementary to the combination of M₂M₃. In sum, the switchesM₁˜M₄ are all active switches working at the grid frequency, e.g., 60Hz, as per the zero transitions of the grid voltage sensor 52 output.

Referring again to FIG. 2, power factor correction (PFC) control logic60 is configured, in general, to manage the operation (i.e., conductionor non-conduction) of the switches S₁˜S₈ in such a way so as to controlthe instantaneous current from AC source 22 so as to be in phase withthe instantaneous voltage of the AC source 22. To achieve a unity ornear unity power factor (i.e., a condition where the grid side voltageand current are in phase), conversion apparatus 20 a includes a gridcurrent sensor 54. In an embodiment, the current sensor 54 is configuredto determine the current through inductor 24, and provide a signal tocontroller 46 that indicates the level of electrical current being drawnfrom AC source 22. This signal is thus a grid current indicative signal.In an embodiment, controller 46 through PFC logic 60 implements powerfactor correction by controlling the gate drive signals for switchesS₁˜S₈. This will be described in greater detail below. Grid currentsensor 54 may comprise conventional components known in the art.

Zero voltage switching (ZVS) logic 62 is configured, in general, tomanage the switches S₁˜S₈ in such a way so that they are turned on andoff preferably with a zero or a near zero voltage. Generally, in orderto maintain zero voltage switching for switch turn-on, before theturning on action, current should reverse flow from the source to drain,which makes the switch voltage drop to zero. Thus, during the switchturn on, the switch only undertakes the current change with a voltagethen-prevailing across the drain to source of the switch always beingclose to be zero, which in turn eliminates the turn-on loss to therebyreach the ZVS turn on. For more information, reference may be made toU.S. application Ser. No. 14/744,998, filed 19 Jun. 2015 (hereinafterthe '998 application, entitled “GATE DRIVE CIRCUIT”), which '998application is hereby incorporated by reference as though fully setforth herein.

FIG. 4 shows timing diagrams of the gate drive signals (i.e., a secondset of switch control signals) to control the operation of switchesS₁˜S8, in a single switching frequency embodiment. In the illustratedembodiment, S₁˜S₈ will be operated at the same switching frequency f_(s)with 50% duty cycle. To achieve the high system power density, theswitching frequency f_(s) should be as high as possible. The gate drivesignals for S₁ and S₂, S₃ and S₄, S₅ and S₆, and S₇ and S₈, arecomplementary. The main control logic 51 is configured to introduce aphase shift between the gate drive signals for S₅ and S₇. Pluralfactors, including the switching frequency f_(s) and the determinedphase shift between S₅ and S₇, together determine the power transferredfrom the primary side of transformer 40 to the secondary side. In otherwords, the above-mentioned factors provide two (2) degrees of freedom tocontrol the transferred power. Meanwhile, in order to achieve ZVS, theS₅-to-S₇ phase shift must fall into a certain range, which restricts theswitching frequency f_(s) to a certain value as well. In FIG. 4, thecurrent through inductor L_(s) is also shown, in timed relationship tothe states of switches S₁˜S₈.

The main control logic 51, in compliance with PFC logic 60 and ZVS logic62, determine at least two parameters, designated g_full and w_full inFIGS. 4-5. The g_full parameter corresponds to a time delay between S₂and S₈ falling edges, while the w_full parameter corresponds to a timedelay between S₁ and S₆ falling edges. The S₅-to-S₇ phase shift isdefined in between g_full and w_full, as graphically shown in FIG. 4.

FIG. 5 is a timing diagram showing waveforms of the above-describedg_full and w_full parameters, which are the two parameters used bycontroller 46 to determine the phase shift between S₅ and S₇. Theparameter fs_full corresponds to the switching frequency f_(s).

In an embodiment, the main control logic 51 is executed by controller 46wherein the functions of rectifier logic 58, PFC logic 60, and ZVS logic62 are realized concurrently. In this regard, the w_full parameter maybe determined by controller 46 in accordance with eqn. (1):

$\begin{matrix}{{{w\_ full}(t)}:=\frac{0.5 \cdot \left( {{{v(t)}} - {{2 \cdot {g\_ full}}\;{(t) \cdot {{v(t)}}}}} \right)}{V\;{2 \cdot {n\_ full}}}} & {{Equation}\mspace{14mu}(1)}\end{matrix}$

where V(t) is measured voltage on the grid side of converter 20 a (i.e.,input node 74—FIG. 2), V2 is the measured output voltage of theconverter at node 80, and n_full is turn ratio of the transformer 40(i.e., N_(s)/N_(p) where N_(s) is the number of secondary turns andN_(p) is the number of primary turns). The parameter g_full in Equation(1) is determined by system designer to achieve ZVS switching. In anembodiment, g_full=0.5(gmin+gmax), where the functions of gmin and gmaxare as set forth in Equations (2) and (3) below:

$\begin{matrix}{{{gmin\_ full}(t)}:=\frac{2\;{{Is\_ full} \cdot L}\;{f \cdot f}\; s\; a}{{{v(t)}} + {V\;{2 \cdot {n\_ full}}}}} & {{Equation}\mspace{14mu}(2)}\end{matrix}$

$\begin{matrix}{{{gmax\_ full}(t)}:=\frac{{V\; 2^{2}{n\_ full}^{2}} - {V\;{2 \cdot {n\_ full} \cdot {{v(t)}}}} + {2 \cdot \left( {{v(t)}} \right)^{2}}}{{{4 \cdot V}\;{2^{2} \cdot {n\_ full}^{2}}} + {4 \cdot \left( {{v(t)}} \right)^{2}}}} & {{Equation}\mspace{14mu}(3)}\end{matrix}$

where gmin is determined by the minimum reactive energy to achieve zerovoltage switching (ZVS) and Is_full is the minimum current to achieveZVS, Lf is the series inductance on primary side (this is represented asL_(s) in FIG. 2), and fsa is the system maximum switching frequency. Thevariables V(t) and V2 is defined above.

In addition, the parameter gmax is determined by the monotonous zone ofcontrolled variable (instantaneous transferred power vs. g_full).

In operation, controller 46 varies the switching frequency f_(s) in realtime during operation. In other words, controller 46 executing maincontrol logic 51 (and subordinate logic modules noted above) varies theoperating switching frequency of S1˜S8 during real time operation.First, the switching frequency of switches S1˜S8 (i.e., fs_full orsometimes referred to as f_(s) herein) and the parameter g_full togetherdetermine the instantaneous power. In addition, the parameter g_full isdefined by g_full=0.5(gmin+gmax) as noted above. Thus, the switchingfrequency fs_full is determined by the instantaneous power and g_full,as in Equation (4) below:

$\begin{matrix}{{{fs\_ full}(t)}:=\left\lbrack {{2 \cdot {{v(t)}} \cdot \frac{\left( {{\left( {1 - {{2\; \cdot {w\_ full}}(t)}} \right) \cdot {{v(t)}}} + {{2 \cdot V}\;{2 \cdot {n\_ full} \cdot {g\_ full}}(t)}} \right)}{\left( {{4 \cdot L}\;{f \cdot {Ptrans\_ full}}(t)} \right)} \cdot \left( {0.5 - {{g\_ full}(t)}} \right)},{fsa}} \right\rbrack} & {{Equation}\mspace{14mu}(4)}\end{matrix}$

In addition, it should be understood that the ZVS implementation mayrestrict switching frequency. In this regard, the g_full and fs_fullparameters together determine transferred power. The g_full parameter isdetermined by ZVS, and the switching frequency is determined by therequired transferred power and the g_full parameter (or ZVS).Additionally, power factor correction (PFC) requires that thetransferred power from the primary side to the secondary side of thetransformer to be in-phase with the input AC voltage, which isdetermined together by the g_full and the fs_full parameters asdescribed above.

Modular AC/DC Conversion Apparatus.

It is desirable to provide an AC/DC electric power conversion apparatussuch as an EV battery charger that is or can be made compatible withboth multi-phase (e.g., 3-phase) and single-phase AC input power.However, conventional attempts have resulted in devices that have poorpower density when operated with single-phase AC input power. Inaccordance with the present teachings, a modular approach is taken thatimproves the power density of such devices when operated withsingle-phase AC input power.

The modular electric power conversion apparatus operates in two modesand, in an embodiment, includes three AC/DC conversion modules. Thefirst mode (FIG. 6) addresses the case where the AC input power signalis a 3-phase input power signal, and in this mode the controller willenable operation of all three AC/DC conversion modules. The individualphases of the 2-phase input are offset from each other, as known, asthus the AC component of the respective output signals of the threeAC/DC conversion modules, being also offset in phase, will tend tocancel each other out. The second mode addresses the case where the ACinput power signal is a single-phase input power signal, and in thismode the controller will enable operation of two of the three AC/DCconversion modules to produce charging power. The controller, however,will only enable aspects of the remaining, third AC/DC conversion modulefor purposes of active filtering so as to reduce the AC component (e.g.,2^(nd) order harmonic) that would otherwise remain present in the outputsignal produced by the first and second AC/DC conversion modules.Repurposing the switches present in the third AC/DC conversion modulewhen operating in the second mode for active filtering purposeseliminates the need for additional switches, micro-controller, and otherfiltering components.

Referring now to FIG. 6, a schematic and block diagram is illustrated ofa modular AC/DC electric power conversion apparatus 98. The apparatus 98is configured to convert a first AC signal (e.g., a 3-phase AC inputpower signal) to a DC output signal on output node 80. Theabove-described topology (FIG. 2) for a single-phase AC power source 22(i.e., conversion apparatus 20 a) can be replicated and applied in aparallel fashion. Apparatus 98 is an embodiment of an application ofthis approach for use with three-phase AC input power. In theillustrated embodiment, no additional output filtering is needed becausethe output current of conversion module handling a respective phase hasa natural 120° difference with respect to each of the other phases, andaccordingly when added together, all the AC components as combined willtend to cancel each other out (i.e., an undesirable ripple can beneutralized).

With continued reference to FIG. 6, a three-phase AC source is shown,for example, as individual sources 22 a, 22 b, 22 c providing AC inputpower having a respective phase (designated phase a, phase b, and phasec). Each source 22 a, 22 b, 22 c produces a respective AC signal whosephase is offset, for example, by 120 degrees, as is conventional. TheAC/AC converter 34 (e.g., indirect matrix converter), the AC/DCrectifier 36 (e.g., H-bridge switching arrangement), and the transformer40 shown in FIGS. 1 and 2—along with other components shown in FIGS. 1and 2—can be replicated for each individual source to form first,second, and third AC/DC conversion modules 100 ₁, 100 ₂, and 100 ₃,respectively. Each of the AC/DC conversion modules 100 ₁, 100 ₂, and 100₃ handle a respective single phase of the multi-phase (3-phase) AC inputpower. The output of each of the AC/DC conversion modules 100 ₁, 100 ₂,and 100 ₃ are electrically connected at output node 80. FIG. 6 furthershows (i) an output capacitance (and associated series resistance)represented as block 102 that is coupled between output node 80 and aground node 82, and (ii) an output inductor (and associated seriesresistance) represented as block 104 coupled between output node 80 andbattery 27. The battery 27, which has a battery voltage V_(b), is alsoshown for frame of reference.

Although not shown in FIG. 6, the controller 46 shown and described inconnection with FIG. 2 will also be provided in this embodiment. Each ofthe AC/DC conversion modules 100 ₁, 100 ₂, and 100 ₃ will beelectrically connected and controlled by the controller 47. In theconfiguration of FIG. 6 for handling 3-phase input power, the controller46 is configured to enable operation of all three of the AC/DCconversion modules 100 _(k), 100 ₂, and 100 ₃. Each conversion module100 _(k), 100 ₂, and 100 ₃ may be operated by controller 47 insubstantially the same manner as described above in connection with asingle electric conversion apparatus 20 a of FIG. 2. In an embodiment,each module 100 _(k), 100 ₂, and 100 ₃ may deliver about 7.2 kW, whichresults in an overall output power (e.g., charging power)>20 kW.Moreover, in the first mode, the AC components (e.g., 2^(nd) orderharmonic) produced by each AC/DC conversion module will tend to canceleach other out, due to the phase offsets described above.

FIG. 7 is a schematic and block diagram of apparatus 98, which is thesame as shown in FIG. 6, except that it is configured for use withsingle-phase AC input power. A single-phase AC input power source 22 ais distributed to each of the AC/DC conversion modules 100 ₁, 100 ₂, and100 ₃. It should be appreciated, however, than when operating withsingle-phase AC input power, a significant second harmonic of the gridfrequency (e.g., 120 Hz in the case of a 60 Hz grid frequency) willappear on the output and will not tend to be cancelled out by thepresence of similar—but offset—harmonics from the other phases. Thepresence of the second harmonic is undesirable for many applications,including charging applications for many current electric vehicle (EV)battery types.

For example, as shown in FIG. 9, a 60 Hz single-phase AC input powersignal 122 (grid power) produces—in the absence of filtering—arelatively large 120 Hz AC component on the output signal (trace 124).In accordance with the present teachings, one of the already-availableAC/DC conversion modules is reconfigured for use in active filtering theoutput.

For single phase operation, the apparatus 98 may be selectivelyconfigured to include active filter circuitry 106, shown in block formin FIG. 7. The apparatus may include (i) a filter housing (not shown) inwhich the active filter circuitry 106 is disposed and (ii) a mainhousing (not shown) in which at least the first, second, and third AC/DCconversion modules 100 ₁, 100 ₂, and 100 ₃ and controller 46 aredisposed. The filter housing includes a first electrical couplingfeature 108 and the main housing includes a second electrical couplingfeature 110 that is complementary with the first coupling feature 108.The first coupling feature 108 is configured to cooperate with thesecond coupling feature 110 to electrically couple the active filtercircuitry 106 with the third AC/DC conversion module 100 ₃. In anembodiment, the first electrical coupling feature 108 may comprise oneof either male or female electrical terminals while the secondelectrical coupling feature 110 may comprises the other one of the maleor female electrical terminals.

In one embodiment, the first coupling feature 108 may include aplurality of male terminals on the filter housing while the secondcoupling feature 110 may include a corresponding plurality of femaleterminals in the main housing. It should be understood, however, thatthe above-mentioned first and second coupling features 108, 110 need notappear at the filter housing or main housing, but rather at otherlocations known in the art. For example, such coupling features mayappear at or on respective circuit board locations.

Additionally, it should be appreciated that the first and secondelectrical coupling features 108, 110 may also perform a mechanicalcoupling function to securely, mechanically couple the active filtercircuitry 106 with or to the apparatus 98 (or portions thereof). In astill further embodiment, the first and second coupling features 108,110 may be configured to allow the active filter circuitry 106 to beselectively insertable and removable (e.g., insertable or removable byhand by a user without the need for tools, electrical soldering, etc.).This aspect allows the apparatus to be readily configured for operationwith single-phase AC input power from a multi-phase (3-phase) inputpower configuration (or vice-versa).

FIG. 8 shows in greater detail the apparatus 98 as configured for singlephase operation. As described above, in the second mode of operation,the controller 46 enables operation of the first and second AC/DCconversion modules 100 ₁, 100 ₂ but only enables a portion of the thirdAC/DC conversion module 100 ₃. In this regard, the controller enablesoperation of the H-bridge switching arrangement 36 c, to which activefilter circuitry 106 is connected. However, the controller 46 disablesthe AC/AC converter 34 c, partially shown in FIG. 8, such that theswitches M1-M4 and S1-S4 are turned OFF.

The active filter circuitry 106 comprises an LC tank circuit having (i)a first branch with a first inductor 112 and a series-connected firstcapacitor 114, and (ii) a second branch with a second inductor 116 and aseries-connected second capacitor 118. When the active filter circuitry106 is plugged into the apparatus 98, the two parallel LC tank circuits(branches) are electrically connected between the H-bridge switchingarrangement 36 c and the output ground node 82.

In an embodiment, the filter housing of the active filter circuitry 106comprises three male terminal, designated 120 ₁, 120 ₂, and 120 ₃, whichcooperate with corresponding female terminals, as described above. Oneend of the first branch LC tank circuit (inductor 112, capacitor 114) isconnected via terminal 120 ₁ to an electrical node in between switchesS5 and S6, while the other end of the first branch is connected viaterminal 120 ₃ to output ground node 82. In addition, one end of thesecond branch LC tank circuit (inductor 116, capacitor 118) is connectedvia terminal 120 ₂ to an electrical node in between switches S7 and S8,while the other end of the second branch is also connected via terminal120 ₃ to output ground node 82. In the illustrated embodiment, the twoparallel branches disposed on the secondary side of the transformer 40 cform the active filter. In an alternate embodiment, based on theinstantaneous power output of the system, and thus needs of the system,one of the branches may be omitted or the controller 46 may beconfigured to disable or otherwise disengage one of the branches.

In an embodiment, the inductance and capacitance values selected may beL=10 uH (for inductor 116) and C=500 uF (for capacitor 118). Theinductance value L for inductor 116 may be selected using conventionalapproaches known in the art. For the value for the capacitance C forcapacitor 118, the value C should be selected sufficiently large toeffectively choke a substantial portion of the reactive power in thesystem/output. In an embodiment where the apparatus comprises a batterycharger, and for purposes of example only, assume that w is the linefrequency, the charger average output voltage is V_(B), and that thecharging current is I=I_(ave)+I_(p) sin(2ωt). Here I_(ave) is theaverage charging current, I_(p) is the peak current of the 120 Hz ripplecomponent in the output. Therefore, the instantaneous power may beexpressed as:P=V _(B) I _(ave) +V _(B) I _(p) sin(2ωt).

The active filter, comprising inductor 116 and capacitor 118, may beconfigured so as to be sufficiently capable to handle the reactive powercomponent: V_(B) I_(p) sin(2ωt). In the worse-case scenario, when C issmall enough, the capacitor voltage is between V_(B) and 0. Namely,

${\frac{1}{2}{C\left( {V_{B}^{2} - 0} \right)}} > {\frac{V_{B}I_{p}}{2\;\pi\; f}.}$

${Therefore},{C > {\frac{I_{p}}{\pi\; f\; V_{B}}.}}$

Referring to FIGS. 9-10, the controller 46, in the second mode ofoperation, is configured to actuate switches S5-S8 of the H-bridgeswitching arrangement 36 c in accordance with a filtering strategy,which engages the active filter circuitry 106 to reduce an AC componentpresent in the output signal (e.g., 2^(nd) order harmonics). As shown inFIG. 9, the trace 124 corresponding to the output current of the AC/DCconversion modules 120 ₁, 120 ₂ (denoted PHASEA/PHASEB in the legend ofFIG. 9) shows a significant 2^(nd) order harmonic of the grid frequency.The controller 46 actuates switches S5-S8 such that S5 and S7 arecontrolled together and likewise S6 and S8 are controlled together, insuch a manner that the active filter current 126 neutralizes the ACcomponent shown in trace 124. This reduction in the 2^(nd) orderharmonic in the output signal is shown as trace 128.

FIG. 10 shows an exemplary duty cycle in accordance with which thecontroller 46 actuates the switch pairs S5, S7 (trace 130) and S6, S8(trace 132). As illustrated, typically the larger the gap between theinstantaneous power and the average power, the larger the duty cycle ofthe switch pairs S5,S7 or S6,S8. However, it should be understood thatdue to the existence of the filter inductor (inductor 116), there may bea phase delay between the duty-cycle waveform and the output current.

To execute this methodology on the above-described structure, thecontroller 46 is configured to perform an initial step of determiningwhether the AC input signal is a multi-phase (e.g., 3-phase) signal orwhether the AC input signal is single phase. The controller 46 can makethis determination by detecting the grid voltage by way of grid voltagesensor 52.

If the controller 46 determines that the AC input power is multi-phase(e.g., 3-phase), then the main control logic 51 branches to the a stepwhich involves operation of the apparatus 98 in the first mode ofoperation. The controller 46 then controls the AC/DC conversion modules100 ₁, 100 ₂, and 100 ₃ as described above for the first mode ofoperation.

If the controller 46 determines, alternatively, that the AC input poweris single-phase, then the main control logic 51 branches to another stepwhich involves operation of the apparatus 98 in the second mode ofoperation. The controller 46 then controls the AC/DC conversion modules100 ₁, 100 ₂, and 100 ₃ as described above for the second mode. In thisregard, the controller 46 is further configured to execute the activefilter duty cycle control logic 64 (FIG. 2). The logic 64, when executedby the controller 64 (i.e., the processor thereof), the controller 46controls the AC/DC conversion modules 100 ₁, 100 ₂, and 100 ₃ in themanner described above. It should be appreciated that the main controllogic 51 associated with a single phase, namely, the control logiccontrolling the operation of the third AC/DC conversion module, needs tobe changed when apparatus switches modes from the first mode to thesecond mode. In addition, only the active filter circuitry 106 needs tobe plugged in (as described above) to complete the conversion from3-phase to single phase operation. The foregoing aspects can shorten aproduct development period.

Conventional AC/DC electric conversion devices capable of handling both3-phase and single-phase AC input power have poor power density whenoperated with single-phase AC input power.

According to the present teachings, an apparatus for converting an ACinput signal to a DC output signal operates in two modes and therebyimproves the power density when operating with single-phase AC inputpower, compared to conventional devices. Embodiments consistent with thepresent teachings may have a power density of ˜5 kW/L. Thus, as notedabove, in the first mode, each AC/DC conversion module separatelydelivers about 7.2 kW, which results in an overall power (e.g., chargingpower) of >20 kW, while in the second mode, the two active first andsecond modules together deliver 7.2 kW*2, or about 14.4 kW as the activeoutput power, while the third AC/DC conversion module (i.e.,secondary-side switches) handle the reactive power through operating theactive filter tank. The single phase operation can deliver approximately⅔ of the rated power (i.e., rated power as when operating from 3-phasepower), or about 14.4 kW. This significantly increases the power densityof the apparatus when running in single phase mode (i.e., much greaterthan conventional 3.3 kW/L).

It should be understood that an electronic control unit as describedherein may include conventional processing apparatus known in the art,capable of executing pre-programmed instructions stored in an associatedmemory, all performing in accordance with the functionality describedherein. To the extent that the methods described herein are embodied insoftware, the resulting software can be stored in an associated memoryand can also constitute the means for performing such methods.Implementation of certain embodiments, where done so in software, wouldrequire no more than routine application of programming skills by one ofordinary skill in the art, in view of the foregoing enablingdescription. Such an electronic control unit may further be of the typehaving both ROM, RAM, a combination of non-volatile and volatile(modifiable) memory so that any software may be stored and yet allowstorage and processing of dynamically produced data and/or signals.

Although only certain embodiments have been described above with acertain degree of particularity, those skilled in the art could makenumerous alterations to the disclosed embodiments without departing fromthe scope of this disclosure. It is intended that all matter containedin the above description or shown in the accompanying drawings shall beinterpreted as illustrative only and not limiting. Changes in detail orstructure may be made without departing from the invention as defined inthe appended claims.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialsdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

While one or more particular embodiments have been shown and described,it will be understood by those of skill in the art that various changesand modifications can be made without departing from the spirit andscope of the present teachings.

What is claimed is:
 1. An apparatus for converting a first AC signal toa DC signal, comprising: an electronic controller including a processorand a memory; and first, second, and third single-phase AC/DC conversionmodule each connected to and controlled by said controller, and whereinrespective output signals from said conversion modules are electricallyjoined at an output node, each conversion module comprising: (i) anindirect matrix converter having an input interface configured toreceive said first AC signal and an output interface configured toproduce a second AC signal; (ii) a transformer having a primary windingand an electrically isolated and magnetically coupled secondary winding;(iii) a coupling inductor in series between said output interface ofsaid indirect matrix converter and said primary winding; and (iv) anH-bridge switching arrangement connected to said secondary winding andconfigured to produce on said output node a respective output signalhaving a DC component and at least one AC component; wherein in a firstmode of operation where said first AC signal comprises a multi-phase ACsignal, said controller is configured to enable operation of said first,second, and third AC/DC conversion modules wherein respective ACcomponents of said respective output signals tend to cancel each otherout; and wherein in a second mode of operation where said first ACsignal comprises a single-phase AC signal, said controller enablesoperation of said first and second AC/DC conversion modules and disablesoperation of said indirect matrix converter of said third AC/DCconversion module, said controller being configured to actuate saidH-bridge switching arrangement of said third AC/DC conversion modulehaving an active filter coupled thereto, according to a filteringstrategy to reduce said AC component of said output signals of saidfirst and second AC/DC conversion modules.
 2. The apparatus of claim 1wherein said active filter is selectively removable.
 3. The apparatus ofclaim 1 wherein said active filter comprises an inductor-capacitor (LC)tank circuit.
 4. The apparatus of claim 3 further comprising a filterhousing in which said tank circuit is disposed and a main housing inwhich at least said first, second, and third AC/DC conversion modulesand said controller are disposed, said filter housing including a firstelectrical coupling feature and said main housing including a secondelectrical coupling feature complementary to said first couplingfeature, wherein said first coupling feature cooperates with said secondcoupling feature to electrically couple said LC tank circuit betweensaid H-bridge switching arrangement and an output ground node.
 5. Theapparatus of claim 4 wherein said first feature is one of male andfemale electrical terminals and said second feature is the other one ofsaid male and female electrical terminals.
 6. The apparatus of claim 1wherein said electronic controller includes main control logic stored insaid memory, said main control logic when executed by said processor isconfigured, when in said first mode of operation, to control operationof said indirect matrix converter and said H-bridge switchingarrangement of said first, second, and third AC/DC conversion module toachieve power factor correction (PFC) and zero voltage switching (ZVS).7. The apparatus of claim 1 wherein said indirect matrix convertercomprises a rectifier responsive to said first AC signal configured toproduce a first direct current (DC) signal, said rectifier including aplurality of rectifier switches arranged in a full bridge arrangement;and wherein said electronic controller includes rectifier logic storedin said memory, said rectifier logic when executed by said processor isconfigured to generate a first set of switch control signalscorresponding to gate drive signals for said plurality of rectifierswitches.
 8. The apparatus of claim 7 further comprising a grid voltagesensor in sensing relation to an AC power source outputting a grid powersignal and configured to generate a grid voltage signal indicate of saidgrid voltage.
 9. The apparatus of claim 8 wherein said rectifier logicis responsive to said grid voltage signal in generating said first setof switch control signals.
 10. The apparatus of claim 7 wherein saidfirst AC signal has a first frequency and said indirect matrix converterfurther comprises a DC to AC converter coupled to said rectifier andconfigured to convert said first DC signal into said second AC signal,said second AC signal having a second frequency that is greater thansaid first frequency, said DC to AC converter including a plurality ofDC to AC switches, wherein said main control logic when executed by saidprocessor of said electronic controller is configured to generate asecond set of switch control signals corresponding to gate drive signalsfor said DC to AC switches.
 11. The apparatus of claim 10 wherein saidH-bridge switching arrangement includes a plurality of H-bridge switchesarranged in an H-bridge configuration, said main control logic whenexecuted by said processor of said electronic controller is configuredto generate a third set of switch control signals corresponding to gatedrive signals for said H-bridge switches.
 12. The apparatus of claim 11wherein said main control logic includes power factor correction (PFC)logic which, when executed by said processor of said electroniccontroller, is configured to generate said second and third sets ofswitch control signals to increase a power factor associated with powerdrawn from said AC source towards one.
 13. The apparatus of claim 12wherein said PFC logic is configured to vary a phase difference in gatedrive signals associated with respective H-bridge switches.
 14. Theapparatus of claim 1 wherein current through said coupling inductor isbi-directional.
 15. The apparatus of claim 1 further comprising anoutput capacitor coupled between said output node and a ground node. 16.The apparatus of claim 1 wherein said electronic controller includesmain control logic stored in said memory, said main control logic whenexecuted by said processor is configured to determine when said firstinput AC signal is said multi-phase signal and enter said first mode ofoperation, said main control logic being configured, when in said firstmode of operation, to control operation of said indirect matrixconverter and said H-bridge switching arrangement of said first, second,and third AC/DC conversion module and wherein said H-bridge switchingarrangement includes a plurality of H-bridge switches arranged in anH-bridge configuration, and wherein said main control logic is furtherconfigured to generate a third set of switch control signalscorresponding to gate drive signals for said H-bridge switches.
 17. Theapparatus of claim 1 wherein said electronic controller includes maincontrol logic stored in said memory, said main control logic whenexecuted by said processor is configured to determine when said firstinput AC signal is said single-phase signal and enter said second modeof operation, said main control logic being configured, when in saidsecond mode of operation: (i) to enable operation of said first andsecond AC/DC conversion modules; and (ii) to disable operation of saidindirect matrix converter and to control operation of said H-bridgeswitching arrangements of said third AC/DC conversion module.
 18. Theapparatus of claim 17 wherein said H-bridge switching arrangementincludes a plurality of H-bridge switches arranged in an H-bridgeconfiguration, and wherein said main control logic includes activefilter duty cycle control logic, which when executed by said processorin said second mode of operation is configured to: generate a fourth setof switch control signals corresponding to gate drive signals for saidH-bridge switches, said active filter being connected to said H-bridgeswitches, said H-bridge switches, when actuated according to said fourthset of switch control signals, reduce said AC component of said outputsignals.